The child is being treated in hospital as concerns for his future spread across the globe. But Chanbua said she would stand by her son. "I feel sorry for him," said Chanbua, who has two other children, aged three and six, and who works on a food stall. "I chose to have him, not to hurt him. I love him. He was in my tummy for nine months; it's like my child. I treat him like my other children."

Chanbua told the ABC network that she refused the couple's request to terminate the pregnancy because in Thai culture it was considered sinful.

"It was like this is the adults' fault and who is he to have to endure something like this even thought it's not his fault?" she said.

Gammy's plight has prompted much soul-searching in Australia.

"I guess it illustrates some of the pitfalls involved in this particular business," said the country's prime minister, Tony Abbott. "It's a very, very, sad story and I hate to think that a child could be abandoned like that."

Rachel Kunde, the executive director of Surrogacy Australia, described the case as shocking.

"Someone's left a baby behind and separated it from its twin and pretty much just disregarded that it was their child, which is something that is just unfathomable for people to think about," she said.

Australia's Department of Foreign Affairs says it is concerned by the reports and is consulting with the Thai authorities.

In Australia, residents of New South Wales, Queensland and the ACT are not allowed to enter a commercial surrogacy agreement overseas.